Out-of-band rejection using saw-based integrated balun and a differential low noise amplifier

Abstract

A front-end module may include an acoustic wave filter with a first and second interdigital transducer electrode. The first interdigital transducer electrode may be single-ended with a first input bus bar that receives an input signal and a second input bus bar connected to ground. The second interdigital transducer electrode may be differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal. The front-end module may include a low noise amplifier (LNA) that outputs a differential signal via a differential output and has a differential input connected to the acoustic wave filter. The LNA may include a first input transistor that receives a first signal from the first output terminal of the acoustic wave filter and a second input transistor that receives a second signal from the second output terminal of the acoustic wave filter.

What is claimed is: 
     
       1. A front-end module comprising:
 an acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal; 
 a low noise amplifier with a differential input electrically connected to the acoustic wave filter, the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output; and 
 a balun electrically connected to the differential output of the low noise amplifier, the balun being a transformer balun that is configured to convert a differential output to a single-ended output. 
 
     
     
       2. The front-end module of  claim 1  wherein the differential output includes a first output node and a second output node. 
     
     
       3. The front-end module of  claim 2  wherein the first output node is connected to a drain of the first input transistor and the second output node is connected to a drain of the second input transistor. 
     
     
       4. The front-end module of  claim 1  wherein the first output terminal is a positive terminal and the second output terminal is a negative terminal. 
     
     
       5. The front-end module of  claim 1  wherein the acoustic wave filter is one of a surface acoustic wave filter, a bulk acoustic wave filter, a temperature compensated surface acoustic wave filter, or a film bulk acoustic wave filter. 
     
     
       6. The front-end module of  claim 1  further comprising a first matching circuit connected between the first output terminal of the acoustic wave filter and the first input transistor of the low noise amplifier. 
     
     
       7. The front-end module of  claim 6  further comprising a second matching circuit connected between the second output terminal of the acoustic wave filter and the second input transistor of the low noise amplifier. 
     
     
       8. The front-end module of  claim 6  wherein the first matching circuit is configured to perform impedance matching between the acoustic wave filter and the low noise amplifier. 
     
     
       9. The front-end module of  claim 1  further comprising a second acoustic wave filter. 
     
     
       10. The front-end module of  claim 9  wherein the differential output of the low noise amplifier includes a first output node and a second output node, and the second acoustic wave filter includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from the first output node and a second input bus bar configured to receive a second input signal from a second output node, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground. 
     
     
       11. The front-end module of  claim 9  wherein the second acoustic wave filter is of a different type or is configured differently than the acoustic wave filter. 
     
     
       12. The front-end module of  claim 1  wherein a connection between the acoustic wave filter and the low noise amplifier is configured to provide balun functionality between the acoustic wave filter and the low noise amplifier without inclusion of a balun circuit element before the differential input of the low noise amplifier. 
     
     
       13. A multi-chip module comprising:
 a stacked filter low noise amplifier circuit including an acoustic wave filter and a low noise amplifier with a differential input electrically connected to the acoustic wave filter, the acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal, and the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output; and 
 a signal converter configured to convert the differential signal from the differential output to a single signal, the signal converter including a balun electrically connected to the differential output of the low noise amplifier, and the balun being a transformer balun that is configured to convert a differential output to a single-ended output. 
 
     
     
       14. The multi-chip module of  claim 13  wherein the signal converter includes a second acoustic wave filter that includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from a first output node of the low noise amplifier and a second input bus bar configured to receive a second input signal from a second output node of the low noise amplifier, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground. 
     
     
       15. The multi-chip module of  claim 13  further comprising a first matching circuit connected between the first output terminal of the acoustic wave filter and the first input transistor of the low noise amplifier, and a second matching circuit connected between the second output terminal of the acoustic wave filter and the second input transistor of the low noise amplifier. 
     
     
       16. The multi-chip module of  claim 13  wherein the differential output includes a first output node and a second output node, and the first output node is connected to a drain of the first input transistor and the second output node is connected to a drain of the second input transistor. 
     
     
       17. The multi-chip module of  claim 13  wherein a connection between the acoustic wave filter and the low noise amplifier is configured to provide balun functionality between the acoustic wave filter and the low noise amplifier without inclusion of a balun circuit element before the differential input of the low noise amplifier. 
     
     
       18. A wireless device comprising:
 an antenna configured to receive a plurality of signals, each signal of the plurality of signals associated with a different frequency band; and 
 a front-end module including an acoustic wave filter, a low noise amplifier with a differential input electrically connected to the acoustic wave filter, and a balun, the acoustic wave filter including a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode being single-ended with a first input bus bar configured to receive an input signal and a second input bus bar connected to ground, and the second interdigital transducer electrode being differential with a first output bus bar connected to a first output terminal and a second output bus bar connected to a second output terminal, and the low noise amplifier including a first input transistor configured to receive a first signal from the first output terminal of the acoustic wave filter and a second input transistor configured to receive a second signal from the second output terminal of the acoustic wave filter, the low noise amplifier configured to output a differential signal via a differential output, the balun electrically connected to the differential output of the low noise amplifier, and the balun being a transformer balun that is configured to convert a differential output to a single-ended output. 
 
     
     
       19. The wireless device of  claim 18  wherein the acoustic wave filter and the low noise amplifier are implemented in a stacked filter low noise amplifier circuit. 
     
     
       20. The wireless device of  claim 18  wherein the front-end module includes a second acoustic wave filter that includes a first interdigital transducer electrode and a second interdigital transducer electrode, the first interdigital transducer electrode of the second acoustic wave filter being differential, and having a first input bus bar configured to receive a first input signal from a first output node of the low noise amplifier and a second input bus bar configured to receive a second input signal from a second output node of the low noise amplifier, and the second interdigital transducer electrode being single-ended with a first output bus bar connected to an output terminal and a second output bus bar connected to ground.